Ce³⁺-Yb³⁺,Tb³⁺-Yb³⁺ And Pr³⁺-Nd³⁺-Yb³⁺ Mixed-Doped Zinc Telluride Glasses For Enhancing The Efficiency Of Silicon Solar Cells

Solar power is a special clean energy source,which will be inexhaustible for a long time.The efficiency of Si solar cells is not very high.One of the main reasons for its poor efficiency is the incomplete absorption of energy from high-energy photons.Down-conversion（DC）luminescence is a process in which one high-energy photon is converted into two or more low-energy photons.Theoretically,in this process,the quantum efficiency（QE）can reach more than 200%.Some rare-earth（RE）ions have been doped into glass by some researchers to prepare DC luminescent glass.A group of RE ions（as mentioned above）only can effectively absorb a small fraction of solar light for DC luminescence.If solar light with multiple different wavelengths can be down converted together,in theory most of the lost energy can be used.In this study,an innovative idea is proposed,that is,the multi-band light-conversion glass doped with three groups of RE ions is prepared.A series of zinc tellurate glasses（Te O₂-Zn O-Na₂O）doped with Ce³⁺-Yb³⁺,Tb³⁺-Yb³⁺and Pr³⁺-Nd³⁺-Yb³⁺,respectively,were prepared by melting quenching method.The crystalline state and interior structure of the prepared glasses are characterized by using X-ray diffraction（XRD）spectra and Raman spectra.And the lowest phonon energy of these glasses is 773 cm^-2.The photoluminescence properties of rare earth ions doped in these glasses are studied.The results show that the near infrared emission（centered at980 nm）of activator ion(Yb³⁺)is observed when the sensitizer ions(Ce³⁺,Tb³⁺,Pr³⁺,Nd³⁺)are excited by using 430 nm,355 nm and 488 nm ultraviolet and visible（UV-VIS）photons,respectively.Subsequently,zinc tellurate glasses doped with Ce³⁺-Yb³⁺,Tb³⁺-Yb³⁺and Pr³⁺-Nd³⁺-Yb³⁺are covered on silicon solar cells,respectively,and then current density-voltage curves（J-V）of the silicon solar cells are measured.The relative efficiencies（Δη）of the silicon solar cells covered with ZT-CY0.50,ZT-TY1.00 and ZT-PNY0.10 glasses are the largest（8.28%,4.05%and 3.52%,respectively）compared with those of their referential silicon solar cell covered with blank glass.Finally,in this light-conversion glass,we doped three groups of RE ions(Ce³⁺-Yb³⁺,Tb³⁺-Yb³⁺and Pr³⁺-Nd³⁺-Yb³⁺),respectively,in a certain order and a certain concentration,where each group of RE ions absorbs a portion of particular solar light.the relative efficiency（Δη）of Si solar cells covered with triple-layers composite glass is increased by 2.37%compared with that of silicon solar cell covered with blank glass.We hope that the triple-layers composite glass will have important applications value in improving the energy efficiency of silicon solar cells in the future.